But when I measure the Vref and Vin on ICL7107 and do the calculation, the Count doesnt show exactly on the 7segment display as in my calculation.
Let say Vin = 0.076 and Vref = 1.293. So, Count = 58.
but my 7segment display 78.

My bench meter is built around the 7107. I added an external reference like the LM4041 and it eliminated a lot of the reading errors. The internal chip heating from the drivers makes the built in reference pretty inaccurate.